1. Field of the Invention
The invention relates to a device for spraying disperse systems.
2. Background Art
In a spray device belonging to the prior art, in a tubular spray head which has passage ducts for the liquid to be sprayed, a cleaning element is slidably mounted which, at the same time is connected to a tip which in a relative movement of the cleaning element to the spray head can slide into an opening of the hole type nozzle to clean this opening (French Patent No. 569,852). In such case, the cleaning is to follow without interruption of the normal function of the spray head.
Further, a spray valve for spraying viscous liquids, which is designed as a needle valve, is known (U.S. Pat. No. 2,794,683). A perforated disk is placed in a spray head of such needle valve concentric to its opening before the hole type nozzle. A plunger, slidable inside of the spray head, has on its head end a cylindrical or conical section which can be shoved through the perforated disk into the opening of the hole type nozzle to press dirt accumulation from such opening of the hole type nozzle.
From German Patent No. 2,724,931, a spray device is known in which a strainer screen and a stripping device are placed in the spray head between intake of the disperse systems and the hole type nozzle. Thus, it is to be achieved that the coarse-grained components of the disperse systems, which can clog the nozzle, are held back and stripped by force.
Especially in spraying of rollers in the hot shaping of sheets, hollow sections (pipes) or other sections with dispersions containing graphite, which takes place over a considerable period, such spray devices have not proved suitable, either because the strainer screen regularly clogged or the installation/removal proved to be too expensive and too time-consuming.